The dialog system was GREAT and you will notice they haven't changed that. The access to powers and such suffered from a lack of things (buttons, whatever) to attach them to on the average controller.

Inventory was a pain but only if you kept a bazillion of everything you found. There was really no reason to keep most of the equipment you found and certainly not the old, outdated stuff from early on in the game. Sorting a bit more would have been better and not resetting some scrolling locations after popping back to them. Using a drag and drop system would be better yet of course.